Tomasz Adamek (right) removed any doubt as to whether he belongs among the best heavyweights by outpointing Chris Arreola on Saturday in Ontario, Calif. Photo / M.L. Preissel

ONTARIO, Calif. — People questioned whether Tomasz Adamek was a real heavyweight going into his showdown with Chris Arreola.

Now they know. The former light heavyweight beltholder and cruiserweight champ is a real heavyweight, as Arreola’s bloody, lumpy face attested to after their stirring 12-round battle at the Citizen’s Business Bank Arena on Saturday.

Adamek (41-1, 27 knockouts), who outboxed and outhustled Arreola to a majority decision (117-111, 115-113 and 114-114), isn’t just a real heavyweight. He’s now a bona fide contender in boxing’s glamor division.

Arreola (28-2, 25 KOs) was THE RING’s No. 6-rated heavyweight going into the HBO-televised 12 rounder. And for six rounds, the resident of nearby Riverside, Calif., looked like the bigger, stronger, and more powerful man, even though Adamek outmaneuvered the L.A. native and beat him to the jab.

However, the ring presence and effectiveness of Arreola, who weighed in at a fleshy 250¾, 33 pounds heavier than Adamek, diminished over the second half of the fight as fatigue and frustration at his inability to cut the ring off on the Polish native set in. Arreola implored Adamek to stand and fight numerous times but the New Jersey-based Pole wisely stuck to his stick-and-move game plan.

Adamek’s professionalism is good and bad news for the heavyweight division, which is in need of entertaining players. His discipline — in his conditioning and his ring intelligence — enabled him to beat Arreola, but it’s also an indication that he won’t be the thrill-a-minute fighter he was at light heavyweight and cruiserweight.

Adamek was one half of at least three Fight of the Year candidates in the lighter weight classes. At heavyweight, where his chin holds up and his speed is good but his power is average, he’ll get the job done.

He’ll still be in good fights, at least by recent heavyweight standards, but fans won’t see him overwhelm his opposition with pressure, volume punching and sheer heart the way he did at 175 and 200 pounds.

At heavyweight, fans will witness more of the 33-year-old veteran’s savvy. They'll see more lateral movement and economical punching.

Adamek connected with 41 percent of the 309 power punches he threw, most of which were straight right hands, according to CompuBox stats.

It wasn’t enough to make for a Fight of the Year candidate, but it was enough to bust up Arreola’s face worse than it was after 10 rounds with Vitali Klitschko.

And it was enough to let the game slugger, the 6,256 fans in attendance, and those watching on TV know that he’s serious about his heavyweight goal.

“This was without question the toughest fight I ever fought,” the always-humble Adamek said after the fight. “This is why I believe I can be a world champion.”